In an air passage switching device described in JP-A-5-238244, two ends of a film member having openings are respectively connected to shafts and are wound on or rewound from the shafts, so that the film member is moved in an air conditioning case. Therefore, the openings of the film member are moved relative to an air passage of the air conditioning case, and an opening portion of the air passage of the air conditioning case is opened and closed.
In this case, because the film member is moved while sliding on the opening portion of the air passage of the air conditioning case, a friction force is caused between the film member and the air conditioning case. Furthermore, because the film member is pressed on the opening portion of the air passage by an air pressure of blown air, the friction force is further increased due to the sliding of the film member.
To overcome the above-described problem, U.S. Pat. application publication No. 2003-0232590 proposes an air passage switching device for preventing a sliding friction of a film member on an opening portion of an air passage of a casing. In this air passage switching device, one end portion of the film member is fixed to a periphery of the opening portion of the air passage, and the other end portion of the film member is fixed to a winding shaft. The winding shaft is moved while rotating, in a direction close to the one end portion of the film member or far away from the one end portion of the film member. Therefore, the other end portion of the film member is wound or rewound around the winding shaft in accordance with the rotation and movement of the winding shaft. Accordingly, a film length from the one end portion of the film member is changed and the opening portion of the air passage is opened and closed by the film member. In this case, the slidable friction is not caused. However, a drive actuator for rotating and moving the winding shaft and a rotation mechanism are mounted outside the winding shaft, and it is difficult to reduce the size of the air passage switching device.